Field of the Invention
The present invention relates to a black resin film (i.e., a decorative material) that has a high bulk strength after heating even when it has a high optical density by using a black pigment, a method for producing the same, a method for producing a capacitance type input device that contains the black resin film and is capable of detecting a touch position of a finger as a change of capacitance, a capacitance type input device obtained by the production method, and an image display apparatus equipped with the capacitance type input device as a constitutional component.
Background Art
In recent years, electronic equipments, such as mobile telephones, car navigation systems, personal computers, ticket vending machines and banking terminals, include ones that are equipped with a tablet type input device on a surface of a liquid crystal display device or the like, in which an indicating image is displayed on an image display region of the liquid crystal display device, and the position where the indicating image is displayed is touched with a finger, a stylus pen or the like by referring to the indicating image, thereby enabling input of information corresponding to the indicating image.
The input device (i.e., a touch-sensitive panel) includes a resistive film type, a capacitance type and the like. However, the resistive film type input device has a two-layer structure containing a film and a glass plate, in which the film is pressed down to short-circuit them, and thus has disadvantages including the narrow operative temperature range and the time-lapse deterioration.
On the other hand, the capacitance input device has such an advantage that a translucent conductive film may be simply formed on a single substrate. The capacitance input device includes, for example, such a type that has electrode patterns that extend to cross each other, and on touching the electrodes with a finger or the like, the change of the capacitance between the electrodes is detected to determine the input position (see, for example, Patent Literature 1).
The capacitance input device also includes such a type that alternating currents having the same phase and the same potential are applied to both ends of the translucent conductive film, and on forming a capacitor by touching with a finger or bringing a finger close thereto, a weak electric current flowing is detected to determine the input position. As the capacitance type input device of this type, such a capacitance type input device is disclosed that contains plural first transparent electrode patterns formed of plural pad portions formed to extend in a first direction and connected through connecting portions, and plural second transparent electrode patterns electrically insulated from the first transparent electrode patterns with an interlayer insulating layer, and formed of plural pad portions formed to extend in a direction intersecting the first direction (see, for example, Patent Literature 2).
A capacitance type touch-sensitive panel containing a front plate having on a non-contact surface thereof a mask layer (which is preferably a black layer or a black resist), a sensor circuit containing a metal trace, and an interlayer insulating layer, which are integrated, is disclosed (see, for example, Patent Literature 3). In this literature, the black layer is disposed to cover and hide the metal trace for transferring signals, so as to prevent the metal trace from being exposed on viewing the substrate or the lens from the above, and thus used as a decorative material for enhancing the appearance of the substrate or the lens. Patent Literature 3 describes that the capacitance type touch-sensitive panel may be reduced in thickness and weight since the front plate is integrated with the capacitance type input device, but does not describe details of the production method, such as the composition of the mask layer, particularly the composition of the decorative material, which is a black layer.
In a circuit of an FPS (flexible printed circuit board), such as a sensor circuit containing a metal trace, generally, a mask layer is provided as a resist using a photosensitive resin composition. As the resist for FPS, for example, the etching resist material described in Patent Literature 4 may be used, and a resist having a target shape may be obtained through exposure and development. Patent Literature 4 describes that the use of a photosensitive resin composition containing an alkali-soluble acrylic resin, a urethane monomer and a particular photopolymerization initiator provides a photosensitive element that has high sensitivity with a low exposure amount and is excellent in adhesion and tent film strength, but fails to describe a photosensitive resin composition containing a black pigment.
Patent Literature 5 describes that the use of a black photosensitive resin composition formed of an alkali-soluble acrylic resin material, a particular crosslinking agent, a photo acid generator and a black pigment, as a shielding film for a color filter may provide a color filter having a black matrix that has a density sufficient for shielding light, has less surface roughness and a high film density, and is free of pattern defects. Patent Literature 5 describes as the crosslinking agent only a methylolated urea, a urea resin, a methylolated melamine, a butylolated melamine, a methylolated guanamine, and alkyl ethers thereof, and in the examples, Nikalac MW-30M (produced by Sanwa Chemical Co., Ltd.) having no acryloyl group but having only an N-methylol group is used, but there is no description of a compound containing an ethylenic unsaturated bond. Patent Literature 5 uses a photo acid generator, but does not describe a photopolymerization initiator.